From: David S. Miller <davem@davemloft.net>
Date: Fri, 11 Jan 2008 05:56:38 +0000 (-0800)
Subject: [TCP]: Do not purge sk_forward_alloc entirely in tcp_delack_timer().
X-Git-Tag: v2.6.25-rc1~1162^2~788
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9993e7d313e80bdc005d09c7def91903e0068f07;p=linux-2.6

[TCP]: Do not purge sk_forward_alloc entirely in tcp_delack_timer().

Otherwise we beat heavily on the global tcp_memory atomics
when all of the sockets in the system are slowly sending
perioding packet clumps.

Noticed and suggested by Eric Dumazet.

Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/include/net/sock.h b/include/net/sock.h
index 786fae858e..902324488d 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -759,6 +759,14 @@ static inline void sk_mem_reclaim(struct sock *sk)
 		__sk_mem_reclaim(sk);
 }
 
+static inline void sk_mem_reclaim_partial(struct sock *sk)
+{
+	if (!sk_has_account(sk))
+		return;
+	if (sk->sk_forward_alloc > SK_MEM_QUANTUM)
+		__sk_mem_reclaim(sk);
+}
+
 static inline void sk_mem_charge(struct sock *sk, int size)
 {
 	if (!sk_has_account(sk))
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 17931be6d5..803d758a2b 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -186,7 +186,7 @@ static void tcp_delack_timer(unsigned long data)
 		goto out_unlock;
 	}
 
-	sk_mem_reclaim(sk);
+	sk_mem_reclaim_partial(sk);
 
 	if (sk->sk_state == TCP_CLOSE || !(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
 		goto out;